AMNIOTIC FLUID & HCG Flashcards
hCG is produced by __________________ of the placenta
syncytiotrophoblast cells
it peaks during the 1st trimester in pregnancy
human chorionic gonadotropin (hCG)
2 subunits of pregnancy test
alpha
beta
it confers specificity for hCG in pregnancy test
beta
hCG, LH, FSH, TSH in pregnancy test
alpha
home-based hCG pregnancy test kit:
principle
enzyme immunoassay
home-based hCG pregnancy test kit:
principle
enzyme immunoassay
home-based hCG pregnancy test kit:
specimen
1st morning urine
home-based hCG pregnancy test kit:
anti-hCG source
rabbit
causes of errors in pregnancy test:
hematuria or proteinuria
malignancies
postpartum and postabortion
premature ovarian failure
chinese herbal medications
false positive
causes of errors in pregnancy test:
dilute urine (low S. G.)
adultered specimen
ectopic pregnancy
too early or too late testing
impending or missed abortion
false negative
hCG bioassays:
female frog
hogben
hCG bioassays:
male frog
Galli-Mainini
hCG bioassays:
virgin female rat
Friedmann/Hoffmann
hCG bioassays:
immature female mice
Ascheim-Zondek
hCG bioassays:
immature female rats
Frank-Berman
hCG bioassays:
female virgin rat
Kupperman
Kelso
main source of nutrients and fluid of the fetus
placenta
specific gravity of urine specimen for pregnancy testing
atleast 1.015
this test is very sensitive, giving positive reactions as early as 10 days after conception
ELISA test
it is present in amnion and provides a protective cushion for the fetus, allows fetal movement, stabilizes the temperature to protect the fetus, and permit lung maturation
amniotic fluid
amniotic fluid volume is regulated by balance between the ___________________ and the _____________
production of fetal urine and lung fluid
absorption from fetal swallowing and intramembranous flow
normal amniotic fluid volume during 3rd trimester
800-1,200 mL
during 1st trimester, ________ of amniotic fluid is from the maternal circulation
35 mL
it is the major contributor to the amniotic fluid volume after the 1st trimester of pregnancy
fetal urine
increased amniotic fluid volume caused by decreased fetal swallowing of urine, fetal structural anomalies, cardiac arrhythmia, congenital infections, chromosomal abnormalities, and neural tube defects
polyhydramnios
decreased amniotic fluid caused by increased fetal swallowing of urine, membrane leakage, urinary tract deformities, congenital malformations, premature amniotic membrane rupture, umbilical cord comopression
oligohydramnios
it is the method of collection for amniotic fluid. Up to 30 mL collected in sterile syringe
amniocentesis
2nd trimester amniocentesis =
assessing genetic defects
3rd trimester amniocentesis =
fetal lung maturity, HDFN
quadruple screening test prior to performing amniocentesis
- alpha-fetoprotein
- human chorionic gonadotropin
- unconjugated estriol (UE3)
- Inhibin A
specimen is placed on ice delivery, kept refrigerated or frozen.
filtration prevents loss of phospholipids
test for fetal lung maturity
specimen is kept at room temperature or 37°C
test for cytogenic studies
specimen is protected from light
test for HDFN
less reliable for amniotic fluid
protein:
glucose:
+
+
less reliable for maternal urine:
protein:
glucose:
more reliable for amniotic fluid
Urea:
Creatinine:
U= <30 mg/dL
C= >3.5 mg/dL
more reliable for maternal urine
Urea:
creatinine:
U= >300 mg/dL
C= >10 mg/dL
differentiation between amniotic fluid and maternal urine is important because _________________
it determines possible premature membrane rupture or accidental rupture of maternal bladder during specimen collection
this test detects premature rupture of membranes (PROM), also used to diagnose early pregnancy (increased estrogen)
fern test
+ fern like crystals in amniotic fluid =
+ protein
+ NaCl
normal color of amniotic fluid
colorless or pale yellow
indicates traumatic tap, trauma, intra-amniotic haemorrhage in amniotic fluid
blood-streaked
indicates HDFN (bilirubin) in amniotic fluid
yellow
suggests presencec of meconium in amniotic fluid
dark green
suggests fetal death in amniotic fluid
dark red-brown
test used for respiratory distress syndrome
fetal lung maturity test
most frequent complication of early delivery and the 7th most common cause of morbidity and mortality
respiratory distress syndrome
____________ normally appears in mature lungs and allows the alveoli to remain open throughout the cycle of inhalation and exhalation
surfactant
it is a reference method and cannot be performed in the presence of blood or meconium
lecithin/sphingomyelin ratio (2:1)
L/S ratio for alveolar stability
lecithin
L/S ratio for alveolar stability
lecithin
L/S ratio that serve as control due to constant production
sphingomyelin
ratio of ____ = mature fetal lungs
> 2.0
amniostat-FLM immunologic test for
phosphatidylglycerol (PG)
not affected by blood or meconium
production og PG is delayed for diabetic mothers
amniostat-FLM
+ bubbles/foam = mature fetal lungs
foam stability (foam/shake test)
measured by fluorescence polarization microscope, phospholipids decrease microviscosity (friction of particle undergoing diffusion)
microviscosity (obsolete test)
adequate FLM in lamenar body count =
> 32,000/uL
type II pneumocytes produce surfactants stored in the form of lamellar bodies
lamellar body count (LBC)
OD 650 nm:
Increase lamellar bodies =
increase OD absorbance
OD of _____________ is equivalent to L/S ratio of > or = 2.0 and the presence of PG
> 0.150
test for fetal age ___________________ = prior to 36 weeks gestation
1.5 to 2.0 mg/dL amniotic fluid creatinine
test for fetal age:
36 weeks (9 months)
> 2.0 mg/dL amniotic fluid creatinine
test for HDFN a. k. a
O. D 450
the oldest routine lab test on amniotic fluid
test for HDFN (O. D 450)
test for HDFN:
normal:
HDFN:
N: increased at 365 nm, decrease at 55o nm
H: increase at 450 nm
HDFN report are plotted on Liley graph:
zone 1
zone 2
zone 3
- non affected or mildly affected fetus
- moderately affected fetus (requires careful monitoring)
- severely affected fetus (requires intervention: labor or exchange transfusion)
test for neural tube defects is a screening test for _________
alphafetoprotein (AFP)
NTD screening test =
increase in neural tube defects
decrease in down syndrome
confirmatory test for NTD
acetylcholinesterase
a birth defect where there is incomplete closing of the back bone and membranes around the spinal cord, mass at lower back
spina bifida (split spine)
the absence of a major portion of the brain, skull, and scalp that occurs during embryonic development
anencephaly
